1. Field of invention
This invention relates to a filter apparatus employing porous hollow fibers, advantageously employable for bacteria from a liquid.
2. Description of prior arts
When filtration of a liquid is carried out in a large amount and in an industrial scale, there is widely used a filter apparatus comprising a housing and a filter cartridge which utilizes a filter member obtained by folding (called "pleating") a plane porous membrane. The cartridge using the pleated porous membrane (which is called "microfilter") for filtration is called "cartridge type microfilter".
In the cartridge type microfilter, microfilters (porous membranes) have different pore sizes are used depending on the purposes such as dust-removing or bacteria-removing from water, juice, alcoholic drinks or pharmaceuticals and air-cleaning, to filter and separate out fine particles or bacteria having sizes of about 0.05 to 10 .mu.m.
As the conventional cartridge type microfilters having been widely used, cartriges having prescribed dimensions in the length and diameter have been generally used. Accordingly, there has been necessarily a limitation in enlarging the membrane area by folding the plane porous membrane used in the cartridge, and also limitation in the filtration capacity.
Recently, porous membrane filters capable of removing more minute solid particles or bacteria have been in demand. However, as the pore size of a porous membrane is made smaller, the filtration capacity becomes smaller.
In place of the porous membrane, a porous hollow fiber having a tubular wall on which a great number of pores are provided have been proposed as filter member. The porous hollow fiber is employed as filter member in the form of a bundle of a great number of porous hollow fibers. However, the previously proposed filter cartriges using porous hollow fibers are not appropriate for use in the known housing for filter cartridge and the advantageous characteristics of the porous hollow fibers are not effectively utilized.